The invention relates to a method for making a friction damper for linen washing machines.
The invention relates, moreover, to a friction damper for linen washing machines, made by the inventive method.
As is known, in linen washing machine friction dampers, the friction element, arranged between the rod and casing of the damper, must be axially restrained in its housing hollow, in order to properly operate.
In prior linen washing friction dampers, this restraining function is performed, according to a first technical solution, by a ring element which is arranged on the top of the hollow shell.
A second prior solution provides to use a suitable undercut portion for restraining the friction element, said undercut portion being made by re-processing the damper shell or casing.
However, it has been found that both the disclosed prior arrangements are not operatively satisfactory and, moreover, they cause a great increase of the cost of the finished product.
Accordingly, the aim of the present invention is to provide a method for making a friction damper for linen washing machines, allowing to make a finished shell or casing, including the necessary housing for receiving therein the friction element, without the need of performing further processing operations after the molding proper.
Within the scope of the above mentioned aim, a main object of the present invention is to provide a finished friction damper of reduced cost and which can be made in a very reduced operating time.
According to one aspect of the present invention, the above mentioned aim and object, as well as yet other objects, which will become more apparent hereinafter, are achieved by a friction damper for linen washing machines, of the type comprising a rod which can be telescopically driven inside a mantle and at least a friction element, arranged between said rod and mantle and housed in an housing cavity, characterized in that said method comprises a first molding step for molding said friction element housing cavity, in which the male element of the mold operates in an axial direction, and a second operating step for making undercut portions for restraining said friction element, said first and second steps being carried out either simultaneously or in succession.
In particular, in the first molding step, the male element of the mold, by operating in an axial direction, provides the damper rod housing hole, the friction housing plane and a plurality of upward opened recesses.
According to a preferred embodiment of the inventive method, the second operating step for forming said friction element housing cavity provides to open the mold, perpendicular to the axis of the damper mantle, to provide a plurality of undercut portions for restraining said friction element and a plurality of slots, formed on the outer surface of said friction element housing cavity or hollow.
According to a further preferred embodiment of the inventive method, the second operating step for making said friction element cavity or hollow provides to use suitable knives, operating from the bottom according to a vertical direction parallel to the mold male element to provide said friction element restraining undercut portions.
The present invention relates, moreover, to a friction damper for linen washing machines, of the type comprising a rod which can be telescopically driven in a mantle and at least a friction element, arranged between said rod and mantle and housed in a cavity therefor, characterized in that said cavity is provided with an housing plane or surface for housing said friction element, a plurality of upward open recesses, and a plurality of restraining undercut portions for restraining said friction element.